The present invention relates generally to multifiber ferrules and, more particularly, to windowless, rectangular, multifiber ferrules that are capable of being preassembled into a connector prior to inserting a plurality of optical fibers into the optical fiber bores defined by the ferrule.
In the process of connectorizing optical fibers, a ferrule is mounted upon the end portions of one or more optical fibers. Thereafter, the other components of the fiber optic connector, such as the spring, the connector housing, the crimp body, and the crimp band, can be assembled. Although the ferrule is principally disposed within an internal cavity defined by the connector housing, the front portion of the ferrule protrudes beyond the connector housing or is otherwise exposed. Consequently, the end portions of the optical fibers that extend through the optical fiber bores defined by the ferrule and that typically protrude slightly beyond the front surface of the ferrule are also exposed following assembly of the fiber optic connector. By mating a pair of fiber optic connectors such that the front surfaces of the ferrules are either brought into contact or are at least disposed proximate one another, the end portions of the optical fibers upon which the fiber optic connectors are mounted will generally be aligned such that optical signals can pass therebetween with a minimum of attenuation.
Initially, single fiber ferrules were developed for mounting upon individual optical fibers. These single fiber ferrules typically have a cylindrical shape and define a single optical fiber bore extending lengthwise therethrough. In order to mount the single fiber ferrule upon an optical fiber, epoxy is injected into the optical fiber bore defined by the single fiber ferrule and the optical fiber subsequently inserted into the optical fiber bore. Once the epoxy has cured, the single fiber ferrule is securely mounted upon the end portion of the optical fiber.
While single fiber ferrules are extremely useful and commonly utilized in a variety of applications, a growing number of applications demand the optical interconnection of a plurality of optical fibers. As such, multi fiber connectors have been developed that include multifiber ferrules for mounting upon the end portions of a plurality of optical fibers to facilitate the interconnection of a plurality of optical fibers. In this regard, Siecor Corporation of Hickory, N.C., has developed a fiber optic connector including a generally cylindrical multifiber ferrule designated as an SC-DC ferrule. Although the generally cylindrical multifiber ferrule defines a plurality of optical bores extending lengthwise therethrough, the generally cylindrical multifiber ferrule is assembled much like a single fiber ferrule in that epoxy is injected into the optical fiber bores and the optical fibers are then inserted through the optical fiber bores such that the optical fibers are secured within the generally cylindrical multifiber ferrule once the epoxy has cured.
While a generally cylindrical multifiber ferrule, such as the SC-DC ferrule developed by Siecor Corporation, is advantageous for a variety of applications, a number of applications require that the ferrule have a substantially rectangular shape in lateral cross-section. See, for example, U.S. Pat. No. 5,214,730 assigned to Nippon Telegraph and Telephone Corporation of Tokyo, Japan, that describes a multifiber ferrule having a substantially rectangular shape in lateral cross-section. Like a cylindrical multifiber ferrule, a generally rectangular multifiber ferrule also defines a plurality of optical fiber bores through which the optical fibers extend. Unlike a cylindrical multifiber ferrule, however, epoxy is not initially injected into the optical fiber bores prior to inserting the optical fibers therethrough. Instead, the generally rectangular multifiber ferrule typically defines a window though which at least a medial portion of the optical fiber bores are exposed. As such, the end portions of the optical fibers can first be inserted through the optical fiber bores and epoxy can then be injected through the window defined by the multifiber ferrule so as to secure the end portions of the optical fibers within the multifiber ferrule once the epoxy has cured.
While the injection of epoxy through a window defined by the multifiber ferrule is effective for securing the optical fibers within a generally rectangular multifiber ferrule, the injection of the epoxy through the window defined by the multifiber ferrule generally complicates the assembly process. In this regard, the injection of epoxy through a window defined by the multifiber ferrule creates overflow that must be cleaned out or it will prevent the free floating of the ferrule in relation to the connector. In addition, by defining a window through one of the side surfaces of the multifiber ferrule, the resulting multifiber ferrule is no longer symmetric. As such, extra care must be taken when mounting the multifiber ferrule within a polishing fixture to insure that the side of the multifiber ferrule that defines the window is mounted in a particular orientation relative to the polishing fixture in order to properly hold the multifiber ferrule during polishing operations.
In many instances, it would be desirable to preassemble at least portions of a fiber optic connector. In this regard, the various components of a multifiber connector could be preassembled prior to mounting the fiber optic connector and, in particular, the multifiber ferrule upon the end portions of a plurality of optical fibers. As such, the multifiber connector could be preassembled in a factory setting and then shipped to the field. Once in the field, the preassembled connector could then be more efficiently mounted upon the end portions of a plurality of optical fibers.
Unfortunately, the requirement that epoxy must be injected through the window defined by a rectangular multifiber ferrule after the optical fibers have been inserted through the optical fiber bores prevents the preassembly of rectangular multifiber connector. In this regard, the multifiber ferrule cannot be disposed within the connector housing until after the multifiber ferrule has been mounted upon end portions of the optical fibers and epoxy has been injected through the window defined by the multifiber ferrule since, in at least some instances, the window is no longer exposed once the multifiber ferrule is disposed within the connector housing. Additionally, there is a chance that the epoxy will extend beyond the window, making the ferrule unable to float freely relative to the connector housing either because of the amount of extra epoxy or the epoxy may have secured the ferrule to the housing. Since the connector cannot be preassembled, a number of separate components must be shipped from the factory to the field. A technician must then completely assemble the multifiber ferrule in the field. In this regard, the technician would initially insert the end portions of the optical fiber through the optical fiber bores defined by the multifiber ferrule and then inject epoxy through the window defined by the multifiber ferrule to secure the optical fibers within the multifiber ferrule. Once the epoxy has cured, the technician can assemble the other components of the fiber optic connector about the multifiber ferrule. As will be apparent, this assembly process is relatively time consuming and is made even more so by having to be performed in the field.
While a variety of fiber optic connectors including various ferrules have been developed, the need still exists for improved multifiber connectors and improved methods for assembling a multifiber connector. In this regard, an improved multifiber connector having a generally rectangular shape in lateral cross-section is sought that can be preassembled prior to inserting the end portions of the optical fibers through the plurality of optical fiber bores defined by the multifiber ferrule. As such, the demands currently placed upon technicians to assemble the multifiber connector in the field would be significantly decreased.
Accordingly, the present invention is directed to a preassembled multifiber connector that obviates the problems due to limitations and disadvantages of the related art.
In one aspect, the invention includes a multifiber connector being at least partially preassembled that includes a connector housing defining a longitudinal internal cavity and a windowless, multifiber ferrule also extending longitudinally between opposed front and rear surfaces and defining a plurality of optical fiber bores that open through the front surface, wherein said ferrule has a plurality of side surfaces with at least a portion of each side surface being planar such that said ferrule is substantially rectangular in lateral cross-section, each side surface of said ferrule also being a continuous surface so as to be free of any window to the optical fiber bores, and wherein said windowless, multifiber ferrule is at least partially disposed within the internal cavity defined by said connector housing to thereby form the multifiber connector that is free of optical fibers such that the multifiber connector is capable of being preassembled prior to inserting a plurality of optical fibers into the optical fiber bores.
In another aspect, a method of preassembling a multifiber connector is provided that includes a windowless multifiber ferrule that extends longitudinally between opposed front and rear surfaces and defines a plurality of optical fiber bores that open through the front surface, wherein the ferrule has a plurality of side surfaces with at least a portion of each side surface being planar such that the ferrule is substantially rectangular in lateral cross-section, each side surface of the ferrule also being a continuous surface so as to be free of any window to the optical fiber bores, and at least partially disposing the windowless multifiber ferrule within an internal cavity defined by a connector housing to thereby form the multifiber ferrule, said disposition of the windowless multifiber ferrule at least partially within the internal cavity defined by the connector housing occurring prior to inserting a plurality of optical fibers into the optical fiber bores such that the multifiber connector is therefore preassembled.
In yet another aspect, a ferrule is provided that is capable of being selectively converted from a windowless configuration to a windowed configuration, the ferrule includes a ferrule body extending longitudinally between opposed front and rear surfaces and defining at least one optical fiber bore opening through the front surface of the ferrule body, wherein said ferrule body comprises at least one side surface, said side surface defining a well that extends therethrough, and wherein said ferrule body further comprises a removable web at least partially covering the well to thereby define a windowless configuration of the ferrule, said web capable of being selectively removed from the well such that the uncovered well forms a window through the side surface of the ferrule that opens into the at least one optical fiber bore to thereby define a windowed configuration of the ferrule.
It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention, and, together with the description, serve to explain the principles of the invention.